Wide word-clock takes a modular approach

[Ishan Karve] took on the challenge of building his own word clock. This is a timepiece that displays the current time in the same syntax you would use if someone asked you what time it was. You’ll find a lot of these projects around, with one of our favorites using etched copper clad as a bezel. But [Ishan] departed for the ordinary by building a clock that is rectangular rather than square. To do so he uses a 16×8 LED matrix that is made up of small modules.

He designed a board that holds a 4×4 LED matrix and includes pin headers on each edge. This way he can arrange these 16-pixel blocks into arrays to make a larger grid. For the clock he used eight boards. These are driven by two MAX7219 chips, with an ATmega168 as the main controller and a DS1307 to keep time. Each LED is isolated by a thick layer of acrylic which as one hole for each pixel. This prevents light from bleeding over into letters that should not be illuminated. Check out the result in the clip after the break.

I personally prefer the somewhat “fuzzier” version that says “It’s a quarter to nine” and increments every five minutes.
Maybe not so precise, but it looks more elegant that “four five minutes past eight” (at 0:44 – coincidentally – in the video).
When you can address the LEDs individually, you can actually merge words that don’t usually appear together, like “threelevenine” or “twone”, to save space and cram more words.